In the production of small objects like pills, capsules, and the like it is necessary to cull out those objects that are undersized. This can be done by visual inspection or weighing, but such a procedure is not adapted to a production line that may be producing thousands of the objects per hour.
Thus, for example, U.S. Pat. No. 4,223,751 proposes a system where the objects are separated and fed pneumatically, one at a time, in a tube through a capacitive weighing system. Those objects that are below the weight threshold are deflected into a cull bin as they are blown out of the conveying tube.
Such an arrangement is highly effective and can operate very quickly. It has, however, the considerable disadvantage that the objects are handled very roughly. This is fine for a durable small object like a gel cap or capsule, but when applied to a pressed tablet or pill can actually chip and damage the product.